walk-dag.go

package main

import (
	"fmt"
	"gonum.org/v1/gonum/graph"
	"gonum.org/v1/gonum/graph/simple"
	"gonum.org/v1/gonum/graph/traverse"
)

// GraphNode is a node in the DAG
type GraphNode struct {
	graph.Node
	Foo string
}

func main () {
	dag := simple.NewDirectedGraph()

	n1 := &GraphNode{
		Node: dag.NewNode(),
		Foo: "bar",
	}
	dag.AddNode(n1)

	n2 := &GraphNode{
		Node: dag.NewNode(),
		Foo: "baz",
	}
	dag.AddNode(n2)

	n3 := &GraphNode{
		Node: dag.NewNode(),
		Foo: "qux",
	}
	dag.AddNode(n3)

	e1 := dag.NewEdge(n1, n2)
	dag.SetEdge(e1)
	e2 := dag.NewEdge(n1, n3)
	dag.SetEdge(e2)

	root := dag.Node(0)

	// walk the graph
	w := &traverse.BreadthFirst{
		Visit: handleVisit,
		Traverse: handleTraverse,
	}
	// keep walking until the end
	w.Walk(dag, root, nil)
}

func handleVisit (g graph.Node) {
	fmt.Printf("Found %+v\n", g)
}

func handleTraverse (e graph.Edge) bool {
	to := e.To()
	fmt.Printf("Edge to %+v\n", to)

	return true
}